1. Field of the Invention
The invention relates generally to the field of Surgery, and more particularly to fluid infusion methods and devices for performing peritoneal dialysis within a patient.
2. Description of the Prior Art
Several of the functions performed by human kidneys are the removal of waste metabolites, the maintenance of fluid, electrolyte and acid-base balances, and hormone and enzyme syntheses.sup.1. Loss of normal kidney function (acute or chronic renal insufficiency) is generally treated through dialysis therapy or transplantation. Transplantation, if successful, restores all the normal functions. Dialysis partially replaces some of the normal kidney functions. For example, it does not replace the hormone or enzyme functions, among others, as evidenced by the greatly reduced blood hemoglobin levels in chronic uremic patients.
Two types of dialysis thereapy are generally employed. Hemodialysis is most commonly used in which the blood is cleansed by passage through an artificial kidney in an extracorporeal membrane system. The waste metabolites diffuse across the membrane and are removed by a washing dialysate solution. Excess fluid is removed by pressure-induced ultrafiltration. The other approach is termed peritoneal dialysis, in which the dialysate solution is infused directly into the abdominal cavity. This cavity is lined by the peritoneal membrane which is highly vascularized. Metabolites are removed by diffusion from the blood to the dialysate across the peritoneal membrane. Excess fluid is removed by osmosis induced by a hypertonic dialysate solution.
Current dialysis treatments are generally performed intermittently under high efficiency conditions. The treatments are usually performed two or three times per week. The length of the treatment depends upon the desired reduction in blood waste metabolite levels, but usually averages 4-6 hours per hemodialysis and 24-48 hours for peritoneal dialysis. The time difference reflects the higher efficiency of hemodialysis, which is a primary reason for its greater popularity. Both procedures result in partial correction of abnormal metabolite, fluid, electrolyte and pH levels during the treatment. Blood metabolite levels are greatly reduced followed by a slow concentration buildup between dialyses. Kjellstrand.sup.2 (1976) has hypothesized that the resulting concentration fluctuations may be detrimental to the patient's health. In fact, high efficiency hemodialyzers are not generally used to their full potential because of a characteristic disorder termed the "disequilibrium syndrome" which develops in certain patients. These patients develop headache, nausea, vomiting, and severe blood pressure alterations after two to three hours of dialysis. This condition often persists throughout the treatment leaving the patient weak and exhausted. It is hypothesized by Arieff.sup.3, et al. (1975) that this syndrome is a result of large intracellular to extracellular concentration (and osmotic) gradients with concomitant fluid shifts, particularly across the "blood-brain barrier".
The Arieff hypothesis is supported by the results of Popovich.sup.4, et al. (1975) who have investigated the consequences of physiological resistance on metabolite removal from the patient-artificial kidney system. Vitamin B-12 and insulin were selected as representative middle molecules in ther investigation. They have shown that very little of the larger test metabolites are cleared from the intracellular body pools during the dialysis treatment. This is caused by the high resistance to mass transfer across the cellular membranes and results in a large post dialysis concentration rebounds as the pools equilibrate in the interdialytic period.
The conventional hemodialysis procedures use an inordinately large amount of dialysate fluid, approximately 450 liters/week. It is contemplated that the procedure of the present invention will utilize approximately 70 liters/week.